tools/lib/api/fs/findfs.c

   1 #include <errno.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <stdbool.h>
   6 #include <sys/vfs.h>
   7
   8 #include "findfs.h"
   9
  10 /* verify that a mountpoint is actually the type we want */
  11
  12 int valid_mountpoint(const char *mount, long magic)
  13 {
  14         struct statfs st_fs;
  15
  16         if (statfs(mount, &st_fs) < 0)
  17                 return -ENOENT;
  18         else if ((long)st_fs.f_type != magic)
  19                 return -ENOENT;
  20
  21         return 0;
  22 }
  23
  24 /* find the path to a mounted file system */
  25 const char *find_mountpoint(const char *fstype, long magic,
  26                             char *mountpoint, int len,
  27                             const char * const *known_mountpoints)
  28 {
  29         const char * const *ptr;
  30         char format[128];
  31         char type[100];
  32         FILE *fp;
  33
  34         if (known_mountpoints) {
  35                 ptr = known_mountpoints;
  36                 while (*ptr) {
  37                         if (valid_mountpoint(*ptr, magic) == 0) {
  38                                 strncpy(mountpoint, *ptr, len - 1);
  39                                 mountpoint[len-1] = 0;
  40                                 return mountpoint;
  41                         }
  42                         ptr++;
  43                 }
  44         }
  45
  46         /* give up and parse /proc/mounts */
  47         fp = fopen("/proc/mounts", "r");
  48         if (fp == NULL)
  49                 return NULL;
  50
  51         snprintf(format, 128, "%%*s %%%ds %%99s %%*s %%*d %%*d\n", len);
  52
  53         while (fscanf(fp, format, mountpoint, type) == 2) {
  54                 if (strcmp(type, fstype) == 0)
  55                         break;
  56         }
  57         fclose(fp);
  58
  59         if (strcmp(type, fstype) != 0)
  60                 return NULL;
  61
  62         return mountpoint;
  63 }